Electrostatic printer with movable style

ABSTRACT

An apparatus for the production of printed images according to electrostatic printing techniques comprising guide means for the electrode arrangement and/or the aforesaid carrier or the counter electrode serving as its support, and means cooperating with the guide means for carrying out a change in the spacing between the electrode arrangement serving to produce the latent charge image and the carrier for the reception of the latent charge image or its counterelectrode.

United States Patent Forgo et 21!.

4 1 May 27, 1975 ELECTROSTATIC PRINTER WITH MOVABLE STYLE Inventors:Gabor Forgo; Erwin Meyer; Karl Moser, all of Zurich, SwitzerlandAssignee: Zellweger Uster AG, Uster,

Switzerland Filed: Aug. 31, 1973 Appl. No.: 393,636

Related US. Application Data 3,661,453 5/1972 McGuire 355/6 3,673,6036/1972 Brock a A 346/74 ES 3,678,219 7/1972 Dennis 340/174] E 3,679,3007/1972 Artelt, Jr. 355/6 3,686,676 8/1972 Howell et a1 346/74 ES3,686,678 8/1972 Robbins et al. 346/74 ES 3,787,722 1/1974 Hatsell346/74 ES Primary Examiner-Bernard Konick Assistant Examiner.1ay P.Lucas Attorney, Agent, or Firm-Werner W. Kleeman [57] ABSTRACT Anapparatus for the production of printed images according toelectrostatic printing techniques comprising guide means for theelectrode arrangement and/or the aforesaid carrier or the counterelectrode serving as its support, and means cooperating with the guidemeans for carrying out a change in the spacing between the electrodearrangement serving to produce the latent charge image and the carrierfor the reception of the latent charge image or its counterelectrode.

20 Claims, 8 Drawing Figures Patented May 27, 1975 3,336,563

6 Sheets-Sheet 1 FIG. 1

Patented May 27, 1975 3,886,563

6 Sheets-Sheet 2 Patented May 27, 1975 6 Sheets-Sheet 3 FIG. 3

% 12 I qr ,7 Fl Eff?" /7 All ISLL-IJ Patented May 27, 1975 6Sheets-Sheet 4 FIG. 4

IOIIOOIII IOIIOI Patented May 27, 1975 6 Sheet s-Sheet 5 Patented May27, 1975 6 Sheets-Sheet 6 ELECTROSTATIC PRINTER WITH MOVABLE STYLECROSS-REFERENCE TO RELATED CASE This is a divisional application of ourcommonly assigned copending United States application Ser. No. 272,047,filed July 14,1972 and entitled Method for Electrostatic Printing,Apparatus for Performance of the Aforesaid Method, Products ProducedThereby, and Use of These Products.

BACKGROUND OF THE INVENTION The present invention relates to a new andimproved apparatus for electrostatic printing.

The invention is particularly concerned with a method for electrostaticprinting in which a latent electrostatic charge image is produced at acarrier having a very high-ohmic layer by a discharge process from anelectrode arrangement neighboring the carrier, wherein the electrostaticcharge image is subsequently developed according to known techniques.These procedures are known and there have also been described in priorart publications equipment for the performance thereof. Although suchknown techniques are extremely outstanding as concerns both the speed oftheir capability of producing printed images and their speed as concernsthe possibilities of varying the printed images produced thereby, assame are applied in a number of different fields, such as for instancethe conversion of digital computer output signals into clear text, stillthey are not suitable for the production of printed images of highquality. In particular, they are not suitable for producing printedimages wherein the line traces or surface elements thereof do notpossses any faulty interruptions, gaps or holes. These defects of theprinted image, which hereinafter are conveniently designated as printingerrors, are extremely disturbing, for example, in the case of codeimages as such are employed for instance for marking articles of sale.Such code images which can possess, for instance, a beam code, acheckerboard-like pattern, a ring structure or the like, are readout forevaluation purposes by means of photoelectric readers. The thusresulting electrical pulse sequence or pulse train then corresponds tothe sequence of the bright and dark locations of the scanned code image.Since the light spot employed for photoelectric scanning and forrealizing high definition or resolution can possess very smalldimensions, for instance fractions of a millimeter the aforementionedprinting errors at the code image can result in an erroneous pulsesequence. In order to prevent such type caused defective pulses orfaulty pulse gaps at the pulse sequence of the photoelectric reader theline traces or surface elements at the code image to be read-out must befree of such defects or faults.

SUMMARY OF THE INVENTION Hence, it is a primary object of the presentinvention to provide a new and improved apparatus for electrostaticprinting which is not associated with the aforementioned drawbacks ofthe prior art and enables considerably increasing the quality of theprinted image in contrast to the known proposals in the art.

Still a further significant object of the present invention relates to anew and improved apparatus for electrostatic printing enabling theproduction of clearly discemable electrostatic printed images in ahighly reliable, accurate and efficient manner, so that read-out of suchimages is possible in error free manner.

Now in order to implement these and still further ob jects of theinvention, which will become more readily apparent as the descriptionproceeds, the invention method for the production of printed imagesaccording to the electrostatic printing techniques is manifested by thefeatures that during at least a portion of the time when there isproduced a latent electrostatic charge image there is carried out achange in the spacing between an electrode arrangement responsible forthe structure of the charge image and the carrier for the reception ofthe latent charge image and/or a counterelectrode.

Not only is the invention concerned with the aforementioned methodaspects but also deals with apparatus for the performance of such methodwhich incorporates guide means rendering it possible to carry out achange in the spacing between the electrode arrangement provided forgenerating the latent electrostatic charge image and the carrierprovided for the reception of the latent charge image or thecounterelectrode.

As also previously indicated the invention is related to a marker,typically label resulting as a product from the practice of the method,and further the use of the thus produced label product for markingarticles, especially articles of sale, as such are found in sundrybusiness establishments.

The terms carrier" or label as used in the context of this disclosure,is not to be considered in a limiting sense, and in fact is intended toconveniently denote any type of printable matter suitable for thepurposes of the invention at which an image can be formed byelectrostatic printing. Similarly the term article of sale is usedbroadly to cover not only articles which are actually sold, but any typeof article, whether sold or not, and intended to be identified by suchlabel".

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be betterunderstood and objects other than those set forth above, will becomeapparent when consideration is given to the following detaileddescription thereof. Such description makes reference to the annexeddrawings wherein:

FIG. 1 is a schematic electrical circuit diagram of a first exemplaryembodiment of the invention;

FIG. 2 illustrates details of the mechanical structure of essentialcomponents of an embodiment of the invention in elevational view;

FIG. 3 is a plan view of the arrangement of FIG. 2;

FIG. 4 illustrates a code image in the form of a beam code;

FIG. 5 illustrates a code image in the form of a checkerboard-likepattern;

FIG. 6 illustrates a code image in the form of a ring structure;

FIG. 7 illustrates a further advantageous constructional form of theinvention; and

FIG. 8 is a schematic illustration of an electrostatic printingapparatus in its entirety.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to describingthe exemplary embodiments of the invention on the basis of theaccompanying drawings there will be initially explained more fully thebasic principles of the invention.

ln the practice of the present invention there is ini tially produced byan electrical discharge a latent electrostatic charge image whichcorresponds to the printed image to be produced and this electrostaticcharge image is subsequently developed in a known manner, for instancein dry fashion by means of a socalled magnetic brush for the applicationof a toner. What is considered to be particularly novel as concerns thisinvention is the manner in which the latent electrostatic charge imageis produced. This charge image results as a consequence of a dischargephenomenon which occurs between a pair of electrodes, namely anelectrode arrangement and a counterelectrode at a carrier e.g., a labelhaving a relatively high-ohmic layer and arranged in the space or regionbetween the aforementioned electrode arrangement and thecounterelectrode. A good discussion of the technique of producingprinted images or pictorial representations in this manner according toelectrostatic printing techniques can be found in, for instance,Taschenbuch der Nachrichtenvevarbeitung, Karl Steinbuch, Second Edition1967, Springer publishers Berlin/Heidelberg/New York, Library ofCongress Catalogue Card Number 67-21079, pages 696 et seq., FIGS. 5.7/5and associated text.

By means of a selector the different individual electrodes of theelectrode arrangement have applied thereto different potentials in orderthat there can be produced at the neighboring carrier a latentelectrostatic charge image possessing a predetermined structurecorresponding to the electrode arrangement and its voltage impingement.Such type charge images produced in this known manner apparently do notpossess any sufficiently homogeneous potential distribution within theline traces or surface elements associated with the thus producedprinted image. Such inhomogeneous potential distribution within therelatively fine line traces or small surface elements of the image canbe hardly experimentally determined owing to the thereat locatedinfinitesimally small quantities of charge. Since, however, even withextensive variations in the developing techniques and the parameters ofthe developing operations there was always again noticed theaforementioned printing errors at printed images produced according tothe heretofore known techniques, it appears that the aforementionedassumption is relevant.

Through extensive experiments and trails it has now been found that bychanging the discharge operations which occur during formation of thelatent electrostatic charge image, that is, by bringing about a changein the spacing between the electrode arrangement and the carrier for theelectrostatic charge image, which change in spacing is undertaken duringthe discharge operations occurring during the formation of the chargeimage, it is possible to produce electrostatic charge images which,after development, form printed images of considerably improved quality.It can therefore be assumed that owing to this change in spacing thepartial discharges required for the formation of the charge image alwaystravel through new paths, and thus there is realized a notable uniformpotential distribution at the line traces or surface elements of thecharge image.

The aforementioned change in spacing produces the noted good resultsboth when such constitutes a reduction as well as an increase in thespacing between the carrier and the electrode arrangement. Thus, it hasbeen found to be reliable if such change in spacing is undertaken up toa point of actual contact of the electrode arrangement and the carrier,without however such contact actually being necessary to realize theaforementionei improvement.

The aforementioned change in spacing can be undertaken either by movingthe electrode arrangement itself or also by carrying out movement of thecarrier for itself, or by simultaneously performing both techniques. Thecarrier is preferably located at the counterelectrode. With suitablemovement of the counterelectrode it is then possible to alter thespacing between the electrode arrangement and the carrier disposed uponthe counterelectrode. The electrode arrangement and its individualelectrodes which have voltage supplied thereto for producing a chargeimage of prescribed configuration, are connected with one pole of thevoltage source via an external current circuit containing the selectorcontrol for the charge image to be produced. The counterelectrode isconnected with the other pole of the voltage source. Depending upon thedesired polarity of the charge image to be produced which, in turn, isdependent upon the polarity of the developer which later is to beemployed, the electrode arrangement is connected with the positive ornegative pole of the voltage source. There can be employed a purelydirect-current voltage or a pulsating directcurrent voltage. Theamplitude of the voltage preferably amounts to about 450 to 1000 volts.

Now, it is advantageous for current limiting purposes followinginitiation of a discharge operation to design the external currentcircuit to the electrode so as to be relatively high-ohmic. A resistancevalue in the order of magnitude of about kiloohms has provided goodresults. Those individual electrodes of the electrode arrangement fromwhich no discharge operation occurs to the carrier and through such tothe counterelectrode, for the purpose of producing a certain chargeimage of a predetermined configuration, are advantageously galvanicallyconnected with a point of considerably lower potential than theremaining individual electrodes furnished with voltage. Preferably theyare galvanically connected with the counterelectrode. This galvanicconnection can be thus advantageously selected to be very high-ohmic,for instance resistance values in the order of magnitude ofapproximately 10 megohms to 100 megohms have provided good results.

The control of the selector control for the selective connection of eachof the individual electrodes of the electrode arrangement with thevoltage source can be undertaken both manually, for instance byactuating key or push button switches as well as with the aid ofelectronic switching circuit arrangements.

Thus, it is possible for instance to introduce a pulse sequencecharacterizing certain information which is to be represented in theform of a printed image, into a shift register having a suitable numberof counting stages. Following the complete input of the pulse sequenceinto the shift register there then appear at transverse outputs of theindividual stages of such shift register logical signals, by means ofwhich it is possible in each instance to actuate a switch, for instance,designed as a Reed relay, associated with one of the relevant stages ofthe shift register and the associated individual electrode of theelectrode arrangement. In this manner there can be produced a chargeimage which corresponds to the aforementioned pulse sequence and theinformation to be expressed thereby. After developing th charge imagethere is obtained in the aforementioned manner a code imagecharacterizing such information. This has been discussed more fully in,and circuitry suitable for this purpose has been disclosed in. ourcommonly assigned, copending United States application, Ser. No. 272,l lI now abandoned, filed July 17, 1972, entitled Method for MarkingArticles of Sale and Apparatus For The Performance Of the AforesaidMethod", to which reference may be readily had.

With the foregoing background in mind, and turning attention nowinitially to the arrangement of FIG. 1 there is shown therein anelectrical circuit diagram of a first exemplary embodiment. Morespecifically, it will be understood that an electrode arrangement 1possesses N-number of individual electrodes E, E attached in anindividually insulated fashion to a base plate 2. Leading from eachindividual electrode E, E is a conductor L, L to each pole ofa switch S,S The relevant other poles of each such switch S, S is connected to aconductor 3 which leads via a resistor 4 to a pole 5, for instance theminus pole, of a suitable voltage source 6. This voltage source 6 has aterminal voltage U of, for instance, 750 volts directcurrent. The otherpole 7, in this example the positive pole, of this voltage source 6 isconnected through the agency of a conductor 8 with a counterelectrode 9spaced at a distance d from the electrode arrangement 1. In theintermediate space between the pair of electrodes l and 9 i.e. theelectrode arrangement 1 and the counterelectrode 9 there is located acarrier I0 for the reception of the latent electrostatic charge image.The carrier 10 is advantageously snugly disposed upon thecounterelectrode 9. The electrode arrangement 1 is mounted in a suitableguide arrangement which has not been particularly illustrated in FIG. 1,but will be considered more fully hereinafter, in such a manner that itcan be displaced in the direction of the double-headed arrow 11. Thus,the spacing d between the electrode arrangement 1 and thecounterelectrode 9 and the surface of the carrier 10 can be readilychanged. Mechanisms suitable for carrying out this spacing change andits mechanical structure will be explained more fully hereinafter inconjunction with FIGS. 2 and 3.

The switches S, S can be activated manually by push buttons or keys or,as already mentioned, there can be provided for instance for thispurpose Reed relays or the like which can be controlled by means of anelectronic control circuit. These switches S, S together with thepossibly provided control circuit form a selector for the selection ofthe individual electrodes of the electrode arrangement to which voltageis to be applied for producing a certain configuration of theelectrostatic charge image.

The specific technique of furnishing individual ones of the electrodeswith power and details of possible circuits suitable for such purposesconstitutes subject matter of our aforementioned copending application,and therefore, will not be further considered herein since same is notthough to be necessary for understanding the subject matter of thisdevelopment. These principles have been merely considered herein to theextent necessary to provide background towards the understanding of theinventive method and equipment.

Hence, turning attention now to FIG. 2 there is disclosed therein apossible constructional form of the essential components of an exemplaryembodiment of the inventive apparatus as depicted in elevational view.FIG. 3 shows the same arrangement in plan view. In all Figures thecorresponding components have been designated with the same referencecharacters.

A shaft 13 is axially displaceably mounted at a support or carrier 12secured to the housing or frame of the equipment. Shaft 13 can bedisplaced in the direction of the double-headed arrow 11. To this end,the shaft 13 possesses a flange 14 with a contact surface 14A. At bothsides of the support 12 there are secured two brackets or supports 15,as best seen by referring to FIG. 3. Between both brackets 15 there ismounted a shaft or axle 16. At this shaft 16 there is pivotably mounteda pivotal frame 17 possessing both of the pivot arms 17A and 17B, afirst connection element 17C and a second connection element 17D. Eachof the pivot arms 17A and 178 carries at its right-hand end, in theillustration of FIGS. 2 and 3, a journal or axle portion 17E and 17Frespectively, pressed or force fitted into the just-mentioned respectiveend of the associated pivot arm and at which there is rotatably arrangeda respective contact roller 17G and 17H.

Furthermore, at the support 12 there is mounted an electromagneticsystem 18 in such a manner that a traction or pull rod 19 comes to restbeneath the connection piece 17D. A coupling piece or element 19A of thetraction or pull rod 19 is adjustably attached thereto. The couplingpiece 19A at least partially engages about the second connection piecel7D of the pivotal frame unit or frame 17. Upon excitation of theelectromagnetic system 18 its traction or pull rod 19 is retracteddownwardly, so that the pivotal frame 17 lowers at the left side of theaxle l6 and at the right side thereof is raised. Owing to this movementthe rollers 17G and 17H press against the contact surface 14A of theflange 14. As a result, the shaft 13 is displaced upwards. By means of aspring 20 arranged in guide housing 21 this shaft 13 is again loweredafter switching-off or deenergizing the electromagnetic system 18. Dueto the action of the electromagnetic system 18 and the spring 20 it isthus possible to displace the shaft 13 in the directions of thedouble-headed arrow 11 i.e. towards and away from the carrier 10 andcounterelectrode 9.

Now upon the shaft 13 there is secured a holder mechanism 22 for theelectrode arrangement 1 (FIG. 1). Opposite the electrode arrangement 1there is located at a certain spacing d the counterelectrode 9. Throughthis space or gap which possesses the height d there is drawn or pulled,by means of a suitable feed mechanism, such as unit 122 to be consideredhereinafter in conjunction with FIG. 8, the carrier 10 for the latentcharge image which is to be imprinted. The carrier 10, in its broadestsense, the label, during the production of the charge image isadvantageously fixedly retained in its momentary position, for instanceunder vacuum action by means of channels or bores 23 at thecounterelectrode 9 connected via a conduit 24 with a suitablecontrollable vacuum device 240 or other source of negative pressure.Also an electromagnetically actuated holddown or clamping mechanism 250for the carrier can be employed. In the embodiment under considerationthe counterelectrode 9 is preferably rigidly secured in the entire frameof the apparatus.

During the production of special printed images, for instance codeimages according to the described method aspects of this development,certain difficulties arise. Now according to a further advantageousphysical manifestation of the invention these difficulties can beeffectively overcome. in order to fully comprehend the same there willnow be considered the special problem which particularly arises duringthe printing of such code or coded characters. hereinafter simplyreferred to as code images or characters. Turning therefore attentionnow to FIGSv 4, S and 6 there are illustrated thereat different types ofarrangements of code images, such as can be used for instance forcharacterizing or marking goods or articles for sale. In FIG. 4 there isshown a beam-type code, in FIG. 5 a checkerboard-type code image and inFIG, 6 a code image having a ring structure, for instance formed of aseries of concentric rings. Of course other configurations of codeimages can be obviously employed without departing in any way from thespirit and scope of the in vention. By means of these code images it ispossible to portray significant information, such as for instance thearticle number of the relevant goods, the price and other sales data inbinary fashion. A black surface element, that is a beam, square or ring,represented in FIGS. 4, 5 and 6 by the cross-hatched portions of thecoded images, can for instance signify the binary value 1 and a whitesurface element of similar geometric configuration can then signify thebinary value 0. Both black and white surface elements can directlyfollow one another. Now for the automatic electro-optical reading ofsuch code images there is scanned in known manner across the relevantcode image under consideration and parallel thereto or in the directionof the indicated arrows a beam of light and the periodically reflectedlight is converted by a photoelectric transducer into a sequence ofelectrical pulses and delivered to a known evaluation device, Thetechnique of reading-out the code characters or code markingsconstitutes sub ject matter of other applications assigned to theassignee of this application and is not necessary for the understandingof the concepts of this development, and therefore will not beconsidered in any greater detail herein.

However, it is here mentioned for the purpose of avoiding false orerroneous reading results it is neces sary that between directlyfollowing black surface elements, in other words between for instancedirectly following black surface elements each of which represents abinary value 1 that there do not occur any white gaps or spaces sincesuch could at least briefly simulate a binary value 0. This problem doesnot arise in alpha numerical representations because there theindividual characters are anyway separated from one another by a more orless wide gap.

The individual electrodes E E (FIG. 1) of the electrode arrangement 1required for producing one of the aforementioned code images or itssurface elements respectively, considering the normally small spacingof, for instance, several tenths of a millimeter between such individualelectrodes E, E of the electrode arrangement 1 and the carrier 10,according to experiencc which has been gained with prior art equipmentmust be chosen to be approximately of the same size as the surfaceelement of the latent electrostatic charge image which is to be producedand the code image which should be recognized following developmentthereof. If it is desired to be able to use all of the surface elementsof the code character in a random sequence, thus for instance the binarycharacter sequence 0000 or 111] or 0101 or 1010 or 0110 or 1001, then itshould be apparent that at least for part of the aforementionedsituations there must be produced in direct succession black surfaceelements, but for another part of the aforementioned situations theremust be produced at the same location different characters, in otherwords black or white characters. Since for initiating the dischargerequired for formation of the charge image only those individualelectrodes associated with black surface elements of the code image areto be connected with the voltage power source, it should be recognizedthat between the individual electrodes E E there must be provided aninsulation which is sufficient for the full voltage, for instanceapproximately 750 volts. Since, however, according to what has beenpreviously stated the individual electrodes are to be chosen to beapproximately of the same size as the surface elements of theelectrostatic charge image to be produced or the code imagerespectively, it should be apparent that in order to apply a sufficientinsulation between the individual electrodes there is just not availablethe necessary space. Moreover, even if for instance there is requiredand used an insulation of, for instance, only 0.2 millimeters, thenstill such results in the fact that between the surface elements of theelectrostatic charge image gaps or spaces would appear which, afterdeveloping of the code image would produce white gaps or spaces betweendi rectly successively following black surface elements. These whitegaps or spaces could, however, render questionable the reliableelectro-optical read-out of the code image.

Now according to an advantageous manifestation of the invention and forthe purpose of overcoming the aforementioned problem, the electrodearrangement 1 is formed of individual electrodes E E which possess aconsiderably smaller dimension in the read-out direction or read-outdirections of the code image produced thereby than the surface elementsof the electrostatic charge image or code image which is to be producedby such electrode arrangement, The width of the individual electrodescan thus, for instance, amount to approximately one-half or one-third ofthe surface ele ment at the charge image or code image which is producedby the individual electrodes. Now in order to be able to obtain surfaceelements of the full width at the charge or code image, notwithstandingthe use of such small individual electrodes, it is contemplated to carryout a desired displacement, for instance between the electrodearrangement 1 and the carrier 10 for the latent electrostatic chargeimage, at least during a portion of the time when such charge image isproduced, and this displacement is undertaken essentially in thedirection of the desired increase in size of the relevant surfaceelement. Moreover, this displacement is advantageously undertaken inalternate directions, This displacement movement can, for instance, becarried out in the form of a toand-fro movement if it is desired to forma code image of the type depicted in FIG. 4. In the event it is desiredto form a code image of the type depicted in FIG. and if such code imageis read-out in the lengthwise and transverse directions, then, there isemployed a lengthwiseand transverse displacement during the productionof the charge image. On the other hand, if it is desired to produce acode image of the type depicted in FIG. 6, then it is advantageous toperform an eccentric circular movement in order that the rings areincreased in size to the full desired size or width at each location.Preferably, there is not only employed a single to-and-fro movement orcircular movement during production of the charge image, rather therelative movement which is carried out between the electrode arrangementand the carrier is repeated a number of times. The amplitude of theaforementioned relative movements can be advantageously selected so asto be even slightly larger than is absolutely necessary for producingthe full nominal surface element width. By virtue of this feature it ispossible to realize a slight overlapping of neighboring black surfaceelements, so that possible tolerances of the apparatus and/or those ofthe discharge operations can be compensated.

Since what is significant is the relative movement between the electrodearrangement and the carrier for the charge image or counterelectrode theapparatus for carrying out this technique can be designed, for instance,such that the carrier is stationary and only the electrode arrangement 1is displaced or vice versa, or in fact both the electrode arrangementand the carrier for the charge image can be displaced.

Owing to the aforementioned measures there is not only brought about awidening of the surface elements, but even more so the uniformity of thecharge distribution within the individual surface elements of the chargeimage is considerably improved. In this way there is achieved the effectthat the code image obtained after developing the charge image possessesa considerably better blackening of the surface elements than would havebeen possible without the aforementioned relative movement between theelectrode arrangement and the carrier. This is of particular importancefor the purpose of producing code images, since, as previouslymentioned, a uniform blackening of the black surface elements providesan improvement in the read-out integrity of the code image.

Now with the foregoing in mind and in conjunction with FIG. 7 there willbe discussed a further advantageous constructional embodiment of theinvention for realizing these objectives. The basic constructionextensively corresponds to the construction according to the arrangementof FIGS. 2 and 3, but on the other hand the holder mechanism 22 for theelectrode arrangement 1 is here modified. Additionally, there are alsopresent in this embodiment certain further components.

Now the constructional embodiment of apparatus depicted in FIG. 7 servesfor producing code images of the type depicted in FIG. 6. The individualelectrodes E E of the electrode arrangement I possess a substantiallysemi-circular ring-shaped configuration. They can, for instance, bearranged according to the technology of printed circuits, for instanceupon an epoxy glass fiber plate. In order to increase wear resistancethey can be galvanically finished, for instance covered with a hard goldor rhodium coating.

The width of the individual ring-shaped electrodes is chosen inconsideration of the insulation required therebetween and can amount to,for instance, only 0.2 millimeters, whereas the spacing to theneighboring in dividual electrode can amount to for instance 0.8millimeters. For increasing the width or size ofa surface element of thecharge image and the code image to be developed, the electrodearrangement 1 can have imparted thereto through the agency of aneccentric mechanism a circular-shaped displacement movement in a planewhich is perpendicular to the shaft 13, defining the aforementionedrelative movement between the electrode arrangement and the carrier.

To this end the electrode arrangement 1 is secured to a guide element25. The guide element 25 possesses a central bore 25A in which there isinserted a ball bearing 258. In this ball bearing 253 there engages aneccentric pin 26A. The guide element 25 is secured against rotation inthat two guide bolts 25C force fitted therewith engage with a respectivebifurcated or fork shaped stationary guide piece 27. The eccentric pin26A is part of an eccentric plate 26 which is adjustably secured in acounterpiece 28 in the transverse direction with regard to the shaft 13.This counterpiece 28 possesses a hub 28A which is secured to the lowerend of the shaft 13.

At the upper end of the shaft 13 there is secured a belt pulley orpulley disk 29. A schematically represented belt 30 connects the beltpulley 29 with a further belt pulley 31 which is seated upon the shaft32A of a drive motor 32. By means of this drive motor 32 the shaft 13can be placed into rotation through the agency of the belt 30. Dependingupon the selected lateral or transverse displacement of the eccentricplate 26 at the counterpiece 28 the eccentric pin 26A carries outsmaller or larger eccentric circular movements which are transmitted viathe guide piece 25 to the electrode arrangement 1. In this way there isrealized the desired transverse or lateral relative movement between theelectrode arrangement 1 and the carrier for the labels as previouslydiscussed.

Now in FIG. 8 there has been schematically depicted the general overallarrangement of an electrostatic printing apparatus suitable for thepractice of the invention and which has been conveniently designated inits entirety by reference character 100. This electrostatic printingapparatus is mounted upon a base plate 101. Base plate 101 carries theindividual cooperating components of the equipment as will be more fullydiscussed hereinafter. Various ones of the individual components thereofare driven, for instance, through the agency ofa belt drive or a chaindrive from a common drive motor M, as will also be explainedhereinafter, and as indicated by the schematic drive connection lines200 shown in the drawing.

The equipment under consideration will be under stood to embody a supplydevice 102 for the markers or carriers, for instance in the form of thelabels 107A to be imprinted and carried by a carrier strip foil 107,also merely referred to as a carrier foil. The supply device 102incorporates a supply roll 104 rotatably mounted upon a fixed shaft oraxle 103. Supply roll 104 is braked by a suitable braking mechanism 105,for instance through the action of a spring-loaded braking roll 105aacting upon the periphery of supply roll 104, in such a manner that thecarrier foil strip 107 which moves over and away from a deflecting roll106 can be tautly withdrawn from the supply roll 104.

The carriers to be imprinted, for example the labels 107A, are appliedto the carrier foil strip 107 at a certain spacing from one another.Carrier foil strip 107 may constitute an impregnated paper strip, apaper strip with a metallic coating applied thereto by vapor depositionor otherwise, or such carrier foil strip can comprise a metallic foilstrip. These labels 107A may advantageously be equipped with aself-adhering layer or coating, as schematically indicated at 107', suchthat they adhere to the carrier foil strip 107 with just such intensitythat they can be conveyed thereon through the printing appartus withoutprematurely falling-off such carrier foil strip 107 during transport.yet it would also be possible to employ a carrier foil strip whichitself has an adhesive layer and at which there is adhesively appliedthe labels which themselves are not adhesive. It should be understoodthat the invention is not generally restricted to any specific type ofcarrier foil strip an electrostatically printable label, since thepractice of the particular development of the invention disclosed hereinaffords the use of many different possibilities for such carrier foilstrip and labels. By way of completeness it might be indicated thatsuitable constructional forms of carrier foil strips and markers(labels) to be imprinted adhering thereto have been disclosed, forinstance, in the commonly assigned, United States application Ser. No.225,111 now abandoned, filed Feb. 10, 1972, and entitled LaminatedPaper, listing as the inventor Arnold Hofer, and also in the commonlyassigned United States application, Ser. No. 263,671, filed June 16,l972, entitled Laminated Article". and listing as the inventor WalterStrohschneider, to which reference can be readily had.

Irrespective of the type of carrier foil strip or label which isemployed, the carrier foil strip 107 is then caused to travel through asuitable control mechanism 108 of a strip feed mechanism 122 forcontinuous or intermittent feed. Although the invention is not intendedto be limited to any specific construction of control mechanism 108, itcan for example contain means, such as photoelectric means 109, a lightbarrier for instance. acted upon by the labels 107A adhering to thecarrier foil strip 107. The labels 107A are either blank, that isnon-printed, or they can already contain imprinted thereon a pre-printedtext, common to all of the labels, for instance data pertaining to acompany, or pre-printed subject matter or any other suitable informationfor the data pattern or the like which later is to be electrostaticallyimprinted. Moreover, special markings of such pre-printed matter or theedge of the labels themselves could be conceivably employed as criteriafor triggering operation of the photoelectric means 109.

The feed mechanism 122 may be controlled in any suitable manner suchthat, for instance, owing to the output signal of a conventional articleweighing or balance device having an automatic data output, or akeyboard arrangement, it can be placed into operation, whereby it issubsequently again brought to standstill by the control mechanism 108 assoon as the next successive label at the carrier foil strip 107 hasassumed the same position as the preceding label prior to placing intooperation such feed mechanism. Details of a balance and keyboardarrangement for obtaining desired output signals have been disclosed inthe aforementioned commonly assigned, United States application, Ser.No. 272,111 now abandoned, filed July 17,

1972, entitled Method For Marking Articles ()1 Sale And Apparatus ForThe Performance Of The Aforesaid Method". Thus, the balance and/orkeyboard arrangement has been simply designated by reference character210 and its connection line with the feed mechanism by referencecharacter 220. As also d closed in detail in such application thebalance and/or keyboard arrangement 210 is connected with a suitableselector control circuit 230 for selectively controlling givenelectrodes of the electrostatic printer 112 in accordance with outputsignals from the unit 210 and characterizing significant informationabout the article to be marked, so as to produce a desired electrostatically charged image at the label. After departing from the controlmechanism 108, the carrier foil strip 107 together with the thereonadhering labels 107A, travels over a further deflecting roll 110 througha slot 110a beneath a guide plate 111 of the electrostatic printer orprinting mechanism 112. The construction and mode of operation of theelectrostatic printer 112 has already been described in conjunction withFIGS. 2, 3 and 7. At this point it is mentioned that owing to stepwiseac tuation of the feed mechanism 122, a label 10713 which is in transitis brought into a predetermined position at a gap or slot 50 between theelectrode arrangement 1 and the counterelectrode 9. By applying asuitable voltage, for instance 750 volts, between the components of theelectrode arrangement 1 and the counterelectrode 9 an electricaldischarge occurs therebetween, so that a latent electrostatic chargeimage is produced upon label 107B.

Now the feed mechanism 122 further advances the carrier foil strip 107,whereupon such travels over a sharp deflecting edge or turning location113 and over further deflecting rolls 115, 116, 117, then about a feedroll 118 and a further deflecting roll 119. The indexing of the feedsteps and the spacing of the individual labels 107A upon the carrierfoil strip 107 are selected so as to be of a magnitude sufficient that,on the one hand, the label which has now been provided with the latentelectrostatic charge image, owing to its greater stiffness in contrastto the carrier foil strip 107, releases from such carrier foil strip atthe edge 113 and, on the other hand, the next successive label at thecarrier foil strip 107 then just assumes the prescribed position betweenthe electrode arrangement 1 and the counterelectrode 9 as previouslyconsidered.

The label provided with the latent electrostatic charge image and whichhas been released from the carrier foil strip 107, has been convenientlydesignated by reference character 107C. A movable element or member 114,for instance an intermittently rotating arm, a roller or equivalentdevice, and which receives at its end face or surface 114A the releasedlabel 107C, is located in the neighborhood of the sharp deflecting edge113, i.e. at the location where the label 107C is released from thecarrier foil strip 107. In order to insure for proper transfer of thelabel it is possible to provide, for instance, a roller formed ofinsulating material and which presses with a slight pressure against theaforementioned end surface 114A. This end surface 114A or the entiremovable element 114 is preferably fabricated from a material, forinstance TEFLON" to which the selfladhering labels 107C do not adheretoo strongly.

The latent electrostatic charge image applied to the labels 107C bymeans of the electrostatic printer or printing mechanism 112, are laterdeveloped in a suitable developer or developing device 130. Thisdeveloper 130 includes a so-called magnetic brush 131. The magneticbrush 131 contains numerous static electrically charged toner particles,the polarity of which is chosen to be opposite to the polarity of thelatent electrostatic charge image. During the advancing movement of thelabels 107C during the rotation of the movable element 114, tonerparticles from the magnetic brush 131 are attracted by the chargedlocations of the electrostatic charge image so that there appears avisible image. The developer may be for example of the type disclosed inthe commonly assigned, copending United States application, Ser. No.268,783, filed July 3, 1972, now US. Pat. No. 3,483,829, granted Jan. 8,1974, and entitled Apparatus For Developing Latent Electrostatic Chargelmages, and to which reference may be readily had.

Preferably the side or face of the label 107C impinged with the latentelectrostatic charge image as it moves from the electrostatic printer112 to the developer 130 is temporarily subjected to the action of acorona discharge from a corona discharge device 150 having an electrode151, this corona discharge having a polarity opposite to the polarity ofthe electrode arrangement 1. As a result, the parts of the label whichshould remain white are charged opposite to the polarity of theelectrostatic charge image. Although this charge is weaker than thecharge at the latent electrostatic charge image this still insures thatthere will occur a repulsion of the charge toner particles from thelocations of the label which should remain white. Owing to thesemeasures the contrast of the electrostatically produced printing imageis considerably improved. Techniques and equipment for improving thecontrast of the electrostatically produced printing image forms subjectmatter of the commonly assigned, copending United States application,Ser. No. 272,064 now abandoned, filed July 14, 1972, and entitled MethodAnd Apparatus For Improving The Contrast During Electrostatic Printing.

It is advantageous to deliver the developed image to a suitable fixingmechanism or fixer 132 in order that the image composed of relativelyweakly adhering toner particles becomes wear or abrasion resistant. Suchfixer 132 can be realized, for instance, by means of an infraredradiation device.

During further movement of the movable element 114 the label 107Cadhering thereto, the electrostatic charge image of which has now beenfixed, is delivered to an opening 125 of the electrostatic printingapparatus 100. The finished labels 107C can be removed at that locationfrom such electrostatic printing apparatus 100. It is also advantageousat this location to allow a suitable stripper or gripper mechanism, forinstance in the form of a fork-like stripper 125a or the like, to actbeneath the finished label 107C in order to facilitate removal of suchlabel.

The carrier foil strip 107 which has been freed from the labels leavesthe feed mechanism 122 through a channel or groove arrangement 123. Thiscarrier foil strip 107 can be collected for instance at a receptacle orcontainer 124 mounted at the outer wall of the housing of theelectrostatic printing apparatus 100. It is however also possible todeliver the carrier foil strip 107 via the channel arrangement 123 towind-up mechanism so that such carrier foil strip can be again reused.This can be advantageous if there is employed as the material for thecarrier foil strip, for instance, a metallic foil or a metallized paperstrip, the costs of which are significant, so that re-use is warranted.

The motor M arranged at the base plate 101 drives through the agency ofchains or belt means and the like the strip feeder or feed mechanism 122and the movable element 114. This drive motor M can also be used fordriving the developer 130. The temporary connection of such systemcomponents with the drive motor M can occur in conventional manner bymeans of suitable electromagentic coupling means, the excitation ofwhich, for instance, can be controlled in any suitable way, as forinstance through the use of a cam disk in a well known manner.

While there is shown and described present preferred embodiments of theinvention, it is to be distinctly understood that the invention is notlimited thereto, but may be otherwise variously embodied and practicedwith the scope of the following claims. ACCORD- INGLY,

What is claimed is:

1. An apparatus for producing printed images by electrostatic printingtechniques, comprising an electrode arrangement and a counterelectrodeserving as a support for a carrier for the reception of a latentelectrostatic charge image, and means for carrying out a change inspacing between the electrode arrangement and the carrier during theapplication of an electrostatic charge image to said carrier in order tocause partial discharges for the formation of the electrostatic chargeimage to travel through different paths across the space between theelectrode arrangement and the carrier to provide a substantially uniformdeposit of charges at the carrier and therefore a substantially uniformpotential distribution within the confines of the electrostatic chargeimage to be produced, so as to induce a substantially uniform coveringof toner particles over the surface of the electrostatic charge image tothereby improve the quality of the electrostatically printed image.

2. The apparatus as defined in claim 1, wherein said means for carryingout said change in spacing includes an axially displaceably mountedholder mechanism for the electrode arrangement.

3. The apparatus as defined in claim 1, including means for moving saidcarrier and said electrode at rangement during the application of anelectrostatic charge inmage to said carrier and relatively of each otherin a plane substantially parallel to the plane of the carrier.

4. The apparatus as defined in claim 1, wherein said means for carryingout a change in spacing comprises a holder mechanism for said electrodearrangement including an axially displaceable shaft, a support member, apivotal frame having a pivot arm pivotally mounted to said supportmember, a flange secured to said axially displaceable shaft, one end ofsaid pivot arm bearing in movable relation on said flange, and anelectromagnetic system connected to the other end of said pivot arm andwhich when energized axially displaces said shaft together with saidholder mechanism for the electrode arrangement relative to the carrier.

5. The apparatus as defined in claim 4, further in cluding spring means,the spring force of which serves to approach said shaft and saidelectrode arrangement towards the carrier for the latent electrostaticcharge image.

6. The apparatus as defined in claim 1, wherein said counterelectrode isprovided with bore means, a vacuum device, and a conduit communicatingsaid bore means with said vacuum device.

7. The apparatus as defined in claim 1, further including anelectromagnetically actuated clamping mechanism for the carrier for thelatent electrostatic charge image.

8. The apparatus as defined in claim 1, wherein said electrodearrangement comprises individual electrodes, and means for furnishingvoltage to predetermined individual electrodes of said electrodearrangement associated with charged surface elements of the latentelectrostatic charge image which is to be produced.

9. The apparatus as defined in claim 1, further including feed means forthe predetermined feed of a carrier foil strip with carriers adheringthereto along a predetermined path of travel.

10. The apparatus as defined in claim 9, further including a coronadischarge device effective at a given location of the predetermined pathof travel of the carriers.

11. The apparatus as defined in claim 10, wherein the latentelectrostatic charge image and the corona discharge device possessdifferent polarity.

12. The apparatus as defined in claim 1, further in cluding a movableelement by means of which a carrier provided with a latent electrostaticcharge image can be selectively advanced towards and away from adeveloper.

13. The apparatus as defined in claim 1, further including a movableelement by means of which a carrier can be advanced towards and removedfrom a corona discharge device.

14. The apparatus as defined in claim 12, wherein said movable elementserves to move a carrier with a developed electrostatic charge imagethereat towards and away from a fixer.

15. The apparatus as defined in claim 1, further including a movableelement by means of which the carrier can be delivered with its chargeimage thereat to an opening of the apparatus for removal therefrom.

16. The apparatus as defined in claim 15, further including mechanismfor removing a carrier provided with the electrostatically producedimage from the movable element.

17. The apparatus as defined in claim I, further including means forreceiving a carrier foil strip freed of carriers originally adheringthereto.

18. The apparatus as defined in claim 1, further including a movablecarrier foil strip for the carriers, means defining a sharp edge at thepath of movement of the carrier foil strip and at which sharp edge thereoccurs detachment of a carrier equipped with a latent electrostaticcharge image from such carrier foil strip.

19. The apparatus as defined in claim 1, further in cluding a developerhaving magnetic brush means for the electrostatic charge image.

20. An apparatus for producing printed images by electrostatic printingat a carrier for receiving a latent electrostatic charge image,comprising a pair of confronting electrodes arranged in spacedrelationship for receiving therebetween a carrier for the latentelectrostatic charge image, the confronting surfaces of said electrodesbeing substantially parallel to each other, and means for altering thespacing between such pair of electrodes while maintaining thesubstantially parallel relation therebetween during the application ofan electrostatic charge image to said carrier in order to cause partialdischarges for the formation of the electrostatic charge image to travelthrough different paths across the space between the pair of electrodesto pro vide a substantially uniform deposit of charges at the carrierand therefore a substantially uniform potential distribution within theconfines of the electrostatic charge image to be produced, so as toinduce a substantially uniform covering of toner particles over thesurface of the electrostatic charge image to thereby improve the qualityof the electrostatically printed image. t I! l

1. An apparatus for producing printed images by electrostatic printingtechniques, comprising an electrode arrangement and a countErelectrodeserving as a support for a carrier for the reception of a latentelectrostatic charge image, and means for carrying out a change inspacing between the electrode arrangement and the carrier during theapplication of an electrostatic charge image to said carrier in order tocause partial discharges for the formation of the electrostatic chargeimage to travel through different paths across the space between theelectrode arrangement and the carrier to provide a substantially uniformdeposit of charges at the carrier and therefore a substantially uniformpotential distribution within the confines of the electrostatic chargeimage to be produced, so as to induce a substantially uniform coveringof toner particles over the surface of the electrostatic charge image tothereby improve the quality of the electrostatically printed image. 2.The apparatus as defined in claim 1, wherein said means for carrying outsaid change in spacing includes an axially displaceably mounted holdermechanism for the electrode arrangement.
 3. The apparatus as defined inclaim 1, including means for moving said carrier and said electrodearrangement during the application of an electrostatic charge inmage tosaid carrier and relatively of each other in a plane substantiallyparallel to the plane of the carrier.
 4. The apparatus as defined inclaim 1, wherein said means for carrying out a change in spacingcomprises a holder mechanism for said electrode arrangement including anaxially displaceable shaft, a support member, a pivotal frame having apivot arm pivotally mounted to said support member, a flange secured tosaid axially displaceable shaft, one end of said pivot arm bearing inmovable relation on said flange, and an electromagnetic system connectedto the other end of said pivot arm and which when energized axiallydisplaces said shaft together with said holder mechanism for theelectrode arrangement relative to the carrier.
 5. The apparatus asdefined in claim 4, further including spring means, the spring force ofwhich serves to approach said shaft and said electrode arrangementtowards the carrier for the latent electrostatic charge image.
 6. Theapparatus as defined in claim 1, wherein said counterelectrode isprovided with bore means, a vacuum device, and a conduit communicatingsaid bore means with said vacuum device.
 7. The apparatus as defined inclaim 1, further including an electromagnetically actuated clampingmechanism for the carrier for the latent electrostatic charge image. 8.The apparatus as defined in claim 1, wherein said electrode arrangementcomprises individual electrodes, and means for furnishing voltage topredetermined individual electrodes of said electrode arrangementassociated with charged surface elements of the latent electrostaticcharge image which is to be produced.
 9. The apparatus as defined inclaim 1, further including feed means for the predetermined feed of acarrier foil strip with carriers adhering thereto along a predeterminedpath of travel.
 10. The apparatus as defined in claim 9, furtherincluding a corona discharge device effective at a given location of thepredetermined path of travel of the carriers.
 11. The apparatus asdefined in claim 10, wherein the latent electrostatic charge image andthe corona discharge device possess different polarity.
 12. Theapparatus as defined in claim 1, further including a movable element bymeans of which a carrier provided with a latent electrostatic chargeimage can be selectively advanced towards and away from a developer. 13.The apparatus as defined in claim 1, further including a movable elementby means of which a carrier can be advanced towards and removed from acorona discharge device.
 14. The apparatus as defined in claim 12,wherein said movable element serves to move a carrier with a developedelectrostatic charge image thereat towards and away from a fixer. 15.The apparatus as defined in claim 1, further including a movable elementby means of which the carrier can be delivered with its charge imagethereat to an opening of the apparatus for removal therefrom.
 16. Theapparatus as defined in claim 15, further including mechanism forremoving a carrier provided with the electrostatically produced imagefrom the movable element.
 17. The apparatus as defined in claim 1,further including means for receiving a carrier foil strip freed ofcarriers originally adhering thereto.
 18. The apparatus as defined inclaim 1, further including a movable carrier foil strip for thecarriers, means defining a sharp edge at the path of movement of thecarrier foil strip and at which sharp edge there occurs detachment of acarrier equipped with a latent electrostatic charge image from suchcarrier foil strip.
 19. The apparatus as defined in claim 1, furtherincluding a developer having magnetic brush means for the electrostaticcharge image.
 20. An apparatus for producing printed images byelectrostatic printing at a carrier for receiving a latent electrostaticcharge image, comprising a pair of confronting electrodes arranged inspaced relationship for receiving therebetween a carrier for the latentelectrostatic charge image, the confronting surfaces of said electrodesbeing substantially parallel to each other, and means for altering thespacing between such pair of electrodes while maintaining thesubstantially parallel relation therebetween during the application ofan electrostatic charge image to said carrier in order to cause partialdischarges for the formation of the electrostatic charge image to travelthrough different paths across the space between the pair of electrodesto provide a substantially uniform deposit of charges at the carrier andtherefore a substantially uniform potential distribution within theconfines of the electrostatic charge image to be produced, so as toinduce a substantially uniform covering of toner particles over thesurface of the electrostatic charge image to thereby improve the qualityof the electrostatically printed image.